docs: def equivalent_reflections(self, hkl):
          """Return all equivalent reflections to the list of Miller indices
          in hkl.
  
          Example:
  
          >>> from ase.lattice.spacegroup import Spacegroup
          >>> sg = Spacegroup(225)  # fcc
          >>> sg.equivalent_reflections([[0, 0, 2]])
          array([[ 0,  0, -2],
                 [ 0, -2,  0],
                 [-2,  0,  0],
                 [ 2,  0,  0],
                 [ 0,  2,  0],
                 [ 0,  0,  2]])
          """
          hkl = np.array(hkl, dtype='int', ndmin=2)
          rot = self.get_rotations()
          n, nrot = len(hkl), len(rot)
          R = rot.transpose(0, 2, 1).reshape((3*nrot, 3)).T
          refl = np.dot(hkl, R).reshape((n*nrot, 3))
          ind = np.lexsort(refl.T)
          refl = refl[ind]
          diff = np.diff(refl, axis=0)
          mask = np.any(diff, axis=1)
          return np.vstack((refl[mask], refl[-1,:]))